Compound expansion internal combustion engine



Dec. 31, 1940'.

c. J. TOTH COMPOUND EXPANSION INTERNAL COMBUSTION ENGINE Filed June 24, 1938 In A In L Patented Dec. 31, 1940 ilNl'iE stares COMPOUND EXPANSION INTERNAL COM- BUSTION ENGINE Charles Joseph Toth, Montevideo, Uruguay 7 Application June 24, 1938, Serial .No. 215,670

In Great Britain July 19, 1937 8 Claims.

The present invention relates to compound expansion internal combustion engines, and particularly to such engines of the two'stroke cycle compression-ignition type.

An object of the present. invention is to provide an improved form of compound internal combustion engine of the two stroke cycle compression-ignition type.

Another object of the invention is to provide a compound engine of this type in which power is applied to the engine during every stroke of the piston, a primary expansion of the working fluid taking place during one stroke and a secondary expansion occurring during the subsequent stroke. 1

In an improved engine in accordance with the invention, stepped. working pistons are employed which on one stroke'thereof perform a working cycle on the high pressure side, corresponding to the first stage expansion and on the subsequent stroke, a working cycle on-the low pressure side corresponding to the second stage of expansion will be performed by the gases exhausted from the high pressure portion of the engine. I

For this purpose, working cylinders are employed which are of difierent sizes in their upper and lower portions respectively and in which the stepped working pistons of different diameters are slidably arranged. The cylinder portion having the smaller size and containing the piston portion of smaller diameter formsthe high pressure portion of this compound engine, Whilst the cylinder portion of larger'size and within which the piston portion of greater diameter slides, forms the low pressure portion of the compound engine. The improved engine'incorporates also a compressor which is necessary to produce the required quantity of precompressed scavenging and charging-air.

The high pressure cylinder portion carries in the cover or head thereof the customary fuelinjection means or valves.

The high pressure cylinder portion has a set of port openings near its lower end which may serve the purpose either of admitting the precompressed scavengingand charging-air or of permitting the exhaust of combustion gases, as the case may be. Consequent upon this, the valve means contained in the head or cover of the high pressure cylinder portion may serve the purposes either of evacuating the combustion gases or of admitting precompressed scavengingand charging-air, as the case may be. In any event, .the cylinderports referred to heretobefore, are controlled, as to'their opening or closing, by the high pressure working piston itself.

The upper part of the low pressure cylinder 5 is arranged to serve the purposes of providing the necessary scavenging-p and charging-air and to that end, this portion of the engine, (which willbe referred to henceforth as the compressor cylinder), is provided with the valve means first to control the admission of atmospheric air and later to control the transfer-of the precompressed air from the compressor cylinder into the corresponding air receiver. y Theexhau'st port. openings or the exhaust valve means of the high pressurecylinder, as the case may be, are conveniently intercommunicated with areceiver thatlmay be located at the side of the low pressure cylinder and within this receiver the partially expanded high pressure com bustion gases, admixed with precompressed scavenging air (an admixture that will be henceforth referred to as the power gases) are stored before their admissioninto thelow pressure cylinder portionfor further work. There are appropriate valve means that at suitable times connect the power gas receiver with the low pressure cylinder portion, in order to admit into this latter named cylinder. the working fluid, that is, the admixture of'partiallyexpanded high pressure combustion gases and precompressed scavenging air. The same valve means or separate valve means, may serve the'purpose-of controlling the final evacuation of the completely expanded power gases from within the low pressure cylinder portion, after they have rendered useful'work within this latter named cyl inder portion on a second stage expansion,

As far as the structural disposition and the operating method ofthe high pressure cylinder portion is concerned, the scavengingand'charging-air enters at one extremity of said' cylinder portion, whereas the partially expanded com-- bustion gases, together with a portion of the precompressed scavenging air that is admixed therewith, areexhausted from said cylinder portion at the other extremity, that is, the scavenging air, we may say, is sweeping'through the whole length of the high pressure cylinder por- 50 tion and, consequently, 'as will be 'evident' to those skilled in the art, for the convenient operation of thiscompound expansion engine it is immaterial whether the scavengingand charging-air is admitted by valve means through the cylinder head and the combustion gases are exhausting through cylinder ports near the lower end of the working'cylinder, or, vice versa, the scavengingand charging-air enters the cylinder by the way of cylinder port openings near the lower extremity of said cylinder and the combustion gases are exhausting under the control of appropriate valve-means, through the cover or head of said cylinder.

It will be understood that any appropriate and conventional type or form of valve means may be employed to secure the satisfactory op-' eration of the present engine; to control the admission of atmospheric air into the compressor. and the subsequent transfer of the precom-.

pressed scavengingand charging-air into the corresponding receiver; to control the admission of precompressed scavengingand char'ging-air into the high pressure cylinder, or else to control the evacuation of power gases from the high pressure cylinder; to control the admissionof power gases into the low pressure cylinder and to control the subsequent" evacuation of the completely expanded power gases from within the low pressure cylinder, valve means of either the pop'p'et-, sleeveorrotary-valve pattern may be used or such of any other suitable known form and method of construction employed.

Neither is it necessary to provide any par- 7 ticular type of actuating gear to control the motion of the different valve means or control organs of this engine, that is to say, said valve means may be actuated either from a single layor cam-shaft or they may be actuated from separate layand cam-shafts, as the case may be, or. in any othe'rwellknown and conventional manner. i

The compound expansion engine forming the object of the present invention may also be built either for operation in a'determined single direction of rotation or the engine may be builtas a direct reversible engine, by adopting in this case, to the layshafts or camshafts'by which the operation of the different valve means is controlled, the corresponding dispositions of reversal.

Various objects and advantages of the invention will appear from the following description of a specific form of the improved engine illustrated by the accompanyingldrawing, the novel features being pointed out in the appended claims.

In the drawing: p

The drawing is a cross, section of the improved engine.

Referring to the engine. structure shown in the drawing, the working cylinder A is of different diameters in its upperandlower portions respectively. The lower portionAh of the smaller diameter constitutes the high pressure portion of the working cylinder and the upper portion Ac of considerably larger diameter forms boththe low pressure portion of .the working cylinder and the compressor cylinder. f

The stepped working piston is slidably arranged so-that its lower portion'Bh may reciprocate with: in the annular high pressure portion Ah of the working cylinder andthe upper and larger portion Bo may reciprocate within the low pressure portion As of the cylinder. The lower face of the piston portion Be is arranged to function as a compressor piston whereas the upper face of this piston portion Bo 'acts as the low pressure working piston of the engine.

The production of precompressed scavenging and charging air by the piston portion Be takes place within the compressor space I. The intake of atmospheric air, at' appropriate times, into this compressor cylinder portion I is controlled by the valve K and the transfer of the precompressed air from within the compressor space into the receiver G is also controlled by the valve K. In the lower portion of the high pressure cylinder portion Ah thereis a valve C which in this form of construction of the engine serves the purpose of evacuating the high pressure cylinder portion, at suitable times, of the partially expanded combustion gases and to convey them by way'of the transfer channel or pipe D into thereceiver space R within which latter space the power gases are stored up to the time of their admission into' the low pressure cylinder portion for further expansion work. The admission of power gases from within the receiver B into the low pressure cylinder portion at suitable times may take place by the valve means P and through the admission channel or clearance space .62.

The final evacuation of the completely expanded power gases from within the low pressure cylinder portion into the exhaust pipe connection W leading to the atmosphera'or an exhaust collector, is by means of the valve P.

The stepped working piston Bh-Bc is connected to the main crank shaft by means of the connecting rod Lh. The low pressure working cylinder is closed by means of a cover or head. The operation oftheadmission valve means C of the high pressure cylinder may be controlled by the camshaft O, and the operation of the admission and exhaust valve means P may be controlled by any appropriate means.

Moreover, in this form of construction of the engine, the power gases leave the high pressure cylinder by the valve means C located at one end of saidcylinder portion whereas'the scavengingand charging-air enters the high pressure cylinder portion, at the other end thereof, through the cylinder ports H. Alsoa single rotary valve P is used to control the admission of power gases into the low pressure cylinder and also to control the exhaust of the completely expanded power gases, from the low pressure cylinder, to the atmosphere, or exhaust mains W.

The operation of the compound expansion in ternal combustion engine forming the subject matter of the present invention maybe characterised asfollows:

The Working piston of the engine is a stepped piston having three working faces of which the piston'portion with the smallest surface is acting as high pressure working piston, the piston portion with the largest surface is acting as low pressure working piston and the piston portion of intermediate size of surface, located between the two first named .portio'ns, is acting, as an aircompressor-piston, within a compressor cylinder which latter is located between the highand low-pressure cylinder portions.

In an enginewith the: cylinders positioned vertically and the high-pressure cylinder portion located in the lower portion of the engine structure, the characteristic operating sequences are:

During every upward stroke of the working piston there is taking place, in the high pressure cylinder, at power stroke on the first stage expansion at the end of which the power gases (that is, partially expanded high pressure combustion gases admixed with precompressed scavenging-air), are transferred into the corre-- sponding receiver; into the compressor cylinder, atmospheric air is being admitted and from the low pressure cylinder, the completely expanded power gases are exhausted.

- During every downward stroke of the working piston, power gases are admitted into the low pressure cylinder from within the corresponding receiver and a power stroke is performed within this cylinder portion on the second stage expansion; in the compressor cylinder, atmospheric air is being precompressed and transferred into the corresponding air receiver; in the high pressure cylinder, during the first part of the downward stroke, the scavenging and supercharging of this cylinder portion is performed by precompressed air admitted into it from the corresponding air receiver and, during the second part of the downward stroke, there is the final compression of thecombustion air within this cylinder portion, it being understood that the scavengingand charging-air enters the high pressure cylinder portion always at the end opposite to that at,which the power gases are evacuated from within said cylinder portion, and preferably it is the total amount of precompressed air produced within the compressor cylinder that passes, for the purposes aforementioned, into the high pressure portion of the engine.

Compound engine units such as are illustrated in the accompanying sketches may be employed alone since it is, what may be termed, a selfcontained engine unit that is-capable of operating satisfactorily without external auxiliary machinery. Nevertheless, preferably several such engine units are combined either with all the cylinders in line or with several of the units grouped or arranged in V-formation or in star or cross formation as the case may be, with the main crankshaft of the engine positioned with its axis horizontally or vertically.

I claim:

1. A two stroke compound internal combustion engine comprising a cylinder having three portions of difierent diameters, the portion with the diameter of intermediate size lying between the portion with the largest diameter and that with the smallest diameter, a piston reciprocable in the cylinder and having three portions of different diameters, the portion with the diameter of intermediate size lying between the portion with the largest diameter and that with the smallest diameter, a rotary shaft driven by the piston and arranged so that the piston portion of largest diameter is most remote from the rotary shaft, means for admitting air into the annular space between the piston and the cylinder at the part of intermediate diameter, means for transferring air after compression in this annular space to the annular space between the piston and the cylinder at the part of the smallest diameter, means for injecting fuel for ignition and primary expansion in this second annular space, a receiver, means for transferring the products of combustion to the receiver, valve means for transferring the products of combustion from the receiver to the end of the cylinder having the larg est diameter for secondary expansion therein, and means for exhausting the expanded gases from this end of the cylinder.

2. A two stroke compound internal combustion engine comprising a cylinder having three portions of different diameters, the portion with the diameter of intermediate length lying between the portion with the largest diameter and that with the smallest diameter, a piston reciprocable in the cylinder and having three portions of different diameters, the portion with the diameter of intermediate length lying between the portion with the largest diameter and that with the smallest diameter, means for admitting air into the annular space between the piston and the cylinder at the part of intermediate diameter, means for transferring air after compression in this annular space to the annular space between the piston and the cylinder at the part of smallest diameter, means for injecting fuel for ignition and primary expansion in this second annular space, valved means for transferring the products of combustion at substantially primary exhaust pressure to the end of the cylinder having the largest diameter for secondary expansion therein, and means for exhausting the expanded the intermediate part of the cylinder, means for admitting air into the annular compression space for precompression, means for transferring the air after precompression to the primary expansion space, means for injecting fuel into the primary expansion space for ignition therein and valved means for transferring the combustion products to the secondary expansion space for secondary expansion.

4. A two-stroke compound internal combustion engine comprising a cylinder, having three axially aligned portions of different diameters, a doublystepped piston reciprocable in the cylinder and forming therewith an annular primary expansion space at the smaller end of the cylinder, a secondary expansion space at the larger end of the cylinder, and an annular compression space at the intermediate part of the cylinder, means for admitting air into the annular compression space for precompression, means for transferring the air after precompression to the primary expansion space, means for injecting fuel into the primary expansion space for ignition therein, a receiver communicating with the primary expansion space and with the secondary expansion space, means to control the transfer of partially expanded gas from the primary expansion space to the receiver, and means to control the transfer of this partially expanded gas from the receiver to the secondary expansion space for a secondary expansion therein.

5. A two-stroke compound internal combustion engine in which a piston is reciprocated in the cylinder during one stroke by the explosion in one end of the cylinder of a combustible mixture and during the succeeding stroke by the further expansion of the products of combustion in the other end of the cylinder comprising a cylinder having three axially aligned portions of different diameters, a doubly stepped piston forming therewith an annular primary expansion space at the smaller end of the cylinder, a secondary expansion space at the larger end of the cylinder and an annular space at the intermediate part of the cylinder in which air for scavenging and charging the cylinder is precompressed, a receiver, a controlled transfer passage connecting the primary expansion space with the receiver,

a transfer passage connecting the receiver withthe exhaust from this space.

7 A two-stroke compound internal combustion engine comprising a cylinder having three portions of diiferent diameters, the portion with the diameter of intermediate size lying between the portion with the largest diameter and that with the smallest diameter, a piston reciprocabie in the cylinder and having three portions of different diametersthe portion with the diameter of intermediate size lying between'the portion with the largest diameter and that with the smallest diameter, a rotary shaft driven by the piston and arranged so that the piston portion of largest diameter is most remote from the rotary shaft, a reservoir, a rotary valve to control both 1e inlet of air into the annular space between the piston and cylinder at the part of intermediate diameter and the transfer of air from this annular space to the reservoir,- a transfer passage controlled'by the piston connecting this reservoir With the annular space between the piston and the cylinder at the part of smallest diameter, means for injecting fuel for ignition and primary expansion in this second annular space, a receiver, means for transferring the products of combustion to the receiver, valve means for transferring the products of combustion from the receiver to the end of the cylinder having the largest diameter for secondary expansion therein, and means for exhausting the expanded gases from this end of the cylinder.

8. A two-stroke compound internal combustion engine comprising a cylinder having three portions of differentdiameters, the portion with the diameter of intermediate size lying between the portion with the largest diameter and that with the smallest diameter, a piston reciprocable in the cylinderand having three portions of different diameters, the portion with the diameter of intermediate size lying between the portion with the largest diameter and that with the smallest diameter, a rotary shaft driven by the piston and arranged so that the piston portion of largest diameter is most remote from the rotary shaft, means for admitting air into the annular space between the piston and the cylinder at the part of intermediate diameter, a reservoir, means for transferring air after compression in this annular space to the reservoir, means for transferring the precompressed air from the reservoir to the annular space between the piston and the cylinder at the part of smaller diameter, means for injecting fuel for ignition and primary expansion in this second annular space, a receiver, means for transferring the products of combustion to the receiver, valve means for transferring the products of combustion from the receiver to the end of the cylinder having the largest diameter for secondary expansion therein, and means for exhausting the expanded gases from this end of the cylinder.

CHARLES J. TOTH. 

